Pandas DataFrame iterating over rows and sum

Question

I have got this pandas DataFrame:

 recipe_name   ingredient_group       weight%
 pudding       milk                     0.60
 pudding 2     sugar                         


        

Answer 1

Use groupby with transform sum:

df['accumulated weight'] = df.groupby(['name','group'])['weight'].transform(sum)
print (df)
    name     group  weight  accumulated weight
0  Appie  elephant      60                  60
1  Henry     tiger      50                 120
2  Henry     tiger      70                 120
3  Laura       cow      30                  30
4  Laura     tiger      20                  20